New Nordic Diet-Induced Weight Loss Is Accompanied by Changes in Metabolism and AMPK Signaling in Adipose Tissue

Context: The molecular mechanisms behind diet-induced metabolic improvements remain to be studied. Objective: This study sought to investigate whether expression of proteins in skeletal muscle or adipose tissue could explain improvements in glucose and lipid homeostasis after weight loss. Design: Volunteers consumed a New Nordic Diet (NND) or an Average Danish Diet for 26 weeks in a controlled, free-living setting. Subjects: Sixty four moderately obese women and men (44 +/- 2 y; body mass index, 31 +/- 1 kg/m(2)). Intervention: Fasting blood samples and biopsies from the vastus lateralis muscle and subcutaneous abdominal adipose tissue (SCAT) were obtained at week 0 and 26. Outcome: Gene and protein expressions were analyzed by real-time PCR and Western blotting. Results: Improved homeostasis homeostatic model of assessment-insulin resistance index and lowered plasma triacylglycerol concentration after NND coincided with molecular adaptations in SCAT but not in skeletal muscle. NND induced greater reduction in fat mass than ADD (-6 +/- 1 kg and -2 +/- 1 kg; P <.01). In SCAT this was associated with increased AMPK and acetyl-CoA carboxylase phosphorylation (P <.05). Concomitantly, NND induced up-regulation of Akt2 and Akt substrate of 160 kDa (P <.05) as well as fatty acid transport protein 4 and membrane associated fatty acid binding protein (P <.05). Indices of increased oxidative capacity were observed, as carnitine palmitoyl transferase 1 mRNA (P =.08) as well as citrate synthase (P =.1) and cytochrome c (P =.05) protein tended to increase. Conclusion: NND-induced metabolic improvements were accompanied by increased AMPK signaling in SCAT, suggesting a role of AMPK in these adaptations. The concomitant up-regulation of key glucose and lipid-handling proteins suggests an improved metabolic capacity in adipose tissue after weight loss.